1. The Field of the Invention
The present invention relates to electrical interconnection test equipment and, more specifically, the invention relates to adapters interfacing with one or more connectors and a wiring analyzer.
2. The Background Art
Cables and harnesses are in common use to interconnect various components of electrical devices. Interconnection enables communication between devices such as a computer and a peripheral device. Cables and harnesses come in various configurations to provide compatibility for the different types of devices. Cables and harnesses are tested during and after manufacturing to ensure proper continuity and the absence of short circuits. Additional tests may also be performed to ensure that the cable or harness will operate as intended in a given application. The equipment that performs these tests is herein called a wiring analyzer.
A challenge in interfacing a wiring analyzer to a cable or wire harness is the identification of the connectors used in the interface and the salient features of the interface. It is important to know the order in which pins in the connector should be counted, the names of the pins in the connector, the number of mating cycles the connector can handle before excessive degradation, and so forth. This information is important in order to verify that two separate test setups can be used to test a cable or harness in a similar way. It would also expedite testing if a wiring analyzer can draw the operator""s attention to the pins in the connector by lighting one or more indicators near the connector.
Accomplishing these tasks normally requires many extra connections to the wiring analyzer, which could otherwise have been used for testing additional wires in the assembly to be tested. One such method is the use of adapter strapping to identify an adapter type by an alphanumeric signature and is disclosed in U.S. Pat. No. 4,620,282 to Shelley, which is incorporated herein by reference. Another method is to include in the adapter one or more data storage devices which use only two wires for communication. This is complicated because such devices currently available, such as the memory tokens manufactured by Dallas Semiconductor, use communication protocols that will not readily adapt to capacitance common for test systems with large numbers of test points.
Thus, it would be an advancement in the art to provide information relating to the adapter to the wiring analyzer in an efficient and economic manner. It would be another advancement in the art to provide a communication protocol that uses electrical connections to meet the needs of large test systems that can be slow due to system capacitance. It would be a further advancement in the art to provide a protocol that provides a visual indication, such as by use of light emitting diodes (LEDs), to draw an operator""s attention to a given connector or pin in a given connector. It would be another advancement in the art to retain a memory of connectors or pins that were previously indicated. Such a system and method are disclosed herein.
The invention is directed towards a device, hereinafter referred to as a smart module, which uses two electrical connections to receive power and clock signals from a wiring analyzer. The electrical connections further provide bi-directional data communication with the wiring analyzer. The smart module may be integrated within an adapter that interfaces one or more connectors to the wiring analyzer. The smart module is so called because it includes a processor or controller and a memory.
The wiring analyzer supplies power to the smart module by impressing a current and voltage across the two electrical connections. The wiring analyzer controls data flow to and from the smart module by issuing clock pulses to the smart module through the two connections. A clock pulse is created by forcing the voltage across the two connections to be reduced for a specified time and then restored. The wiring analyzer transmits data to the smart module while transmitting each clock pulse by varying the voltage supplied to the smart module during the clock pulse.
If voltage supplied during the clock pulse is less than a specified negative voltage, a data bit is interpreted to be of one state, otherwise it is interpreted to be of the other state. The smart module transmits data to the wiring analyzer by varying the load that it presents to the two connections to the wiring analyzer upon receiving a clock pulse from the wiring analyzer. The smart module transmits a data bit of one state by presenting a large load, and transmits a data bit of the other state by presenting a small load to the connections to the wiring analyzer. The data bit is presented continuously until the wiring analyzer presents another clock pulse to the smart module, or until the wiring analyzer reduces the power supplied to the smart module for a specified time. The communication protocol transmits data in the described manner to facilitate the use of smart modules in large test systems.
The smart module may also include one or more indicators, such as LEDs, that are in electrical communication with the processor. The wiring analyzer transmits a signal to the smart module that causes the smart module to divert power supplied by the wiring analyzer to a selected indicator.
The invention reduces the number of electrical connections required to store information about an adapter and an interface with a cable or wire harness. The invention further provides one or more indicators to draw an operator""s attention to a given connector in an interface or pin in a given connector.